This study is an industry sponsored Phase III Safety and Efficacy Study of Synagis through the PPRU. This is a monoclonal passive vaccine for respiratory syncytial virus. The purpose of this study was to evaluate the safety and efficacy of Synagis in children under 2 years of age with complex congenital heart disease. The patients received five immunizations over a period of five months with monitoring of all adverse reactions and incidence of respiratory syncytial virus infection. This is a multi-center study. Five patients were enrolled at The Children's Hospital of Philadelphia.